Nickel base alloy



April 12, 1949. e. A. BAKER ET AL NICKEL BASE ALLOY Filed May 3, 1947INVENTOR euv A. BAKER JQQAES A. PARSONS ATTORNEYS Patented Apr. 12, 1949UNITED STATES PATENT OFFICE NICKEL BASE ALLOY Guy A. Baker and James A.Parsons, Dayton, Ohio, assignors to The Duriron Company, 1110., Dayton,Ohio, a corporation of New York Application May 3, 1947, Serial No.745,745

- 1 Claim. 1

The present invention relates to nickel base alloys and is concernedprimarily with an allo of this type which has improved corrosionresistant properties.

A nickel base alloy of the type with which this invention is concernedincludes, as essential elements, nickel, chromium, molybdenum, iron, andsmall amounts of carbon, manganese, and silicon. In the past many of thealloys of this type have also included tungsten. One of the propertiesrequired of such an alloy is that it be corrosion resistant.

This invention has in view, as its foremost objective, the provision ofa nickel base alloy of this type which has corrosion resistantproperties to a degree higher than anything heretofore attained.

To the end of improving the corrosion resist ance in an alloy of thischaracter the tungsten is completely eliminated. Moreover, the ferrouscontent is held down to a proportion lower than anything heretoforeattained and the carbon con tent is also kept down to a minimum which isbelow anything heretofore achieved in a nickel base alloy of this typethat includes iron.

A highly important object of the invention is to provide a nickel basealloy including a ferrous content because with iron present the productexhibits many of the characteristics of stainless steel and whichcharacteristics are extremely desirable. However, in providing thisingredient it is important that its proportion be held down as low as isconsistent with obtaining the desired ferrous properties. With thiscondition obtaining the remainder of the allow is enriched as to itsnickel, chromium, and molybdenum contents.

With a ferrous content present in a nickel base alloy of this type itbecomes important to keep the amount of carbon present down to as smalla degree as possible as this increases the corrosion resistantproperties of the alloy.

Accordingly, a further object of the present invention is to provide anickel base alloy of the type indicated which includes iron and in whichcarbon is present in a proportion of about .07 per cent.

A further object of the invention is to provide a nickel base alloy, ofthe character aforesaid, in which nickel is present in the proportion ofabout 60 per cent, substantially equal proportions of molybdenum andchromium each in the amount of about 18 per cent, and 3 per cent ironwith the remainder of the alloy made up of .07 per cent carbon andtraces of manganese and silicon.

It will be noted that there are three factors which mutually contributeto provide improved corrosion resistant properties. In the first place,the alloy is free of tungsten which is an important factor when iron ispresent. Secondly, the iron content is held down lower than anythingheretofore achieved in this art and, thirdly, the carbon content is apercentage which is distinctly new in a nickel base alloy of this typehaving a ferrous content. The alloy provided by this invention is notonly highly resistant to corrosion but it is also machinable which isanother desirable factor.

Various other and more detailed objects and advantages such as arise inconnection with carrying out the above noted ideas in a practicalembodiment will in part become apparent and in part be hereinafterstated as the description of the invention proceeds.

The invention, therefore, comp-rises a nickel base alloy having aferrous content of 3 per cent or less, a carbon content of .07 per cent,and in which nickel is present in a proportion of. about per cent withthe remainder of the alloy made up of substantially equal parts ofchromium and molybdenum.

For a full and more complete understanding of the invention, referencemay be had to the following description and accompanying drawing whereinthe figure is a microphotograph depicting the surface of an alloyenlarged 200 times and made in accordance with the precepts of thisinvention.

The alloy of this invention includes certain ingredients the proportionsof which are critical. Thus, carbon should be present in a proportionranging from .04 to .10 per cent with .07 per cent the optimum. Ironmust be included but in a proportion no greater than 3 per cent; thatis, the amount of iron must never exceed 3 per cent.

Nickel should be present in the proportion of about 60 per cent whilechromium and molybdenum are present in equal proportions each making upabout 18 per cent of the alloy.

At this point it is well to note that the percentages referred to ingiving the proportions are by weight.

Following the above noted principles a typical example of an alloy whichembodies the invention is set forth as follows:

Percent Chromium 17.00 Molybdenum 17.00 Silicon 1.50 Manganese .75Carbon .07 Iron 3.00 Nickel 60.68

Of the proportions above specified some slight deviation from the exactamounts indicated is permissible. Thus, chromium and molybdenum may bepresent in proportions of 18 per cent rather than the 17 per centindicated although it is important to remember that the amount of oneshould be substantially identical with that of the other. Moreover, theiron content may be less than the 3 per cent indicated as this figure isintended to denote the maximum iron content permissible. In the eventthat the iron is present in less than 3 per cent the difierence will becompensated for by an increase in the amount of nickel. While the carboncontent may be varied over the range from .04 to .10 per cent, the .07per cent specified is believed to be the most desirable.

Another example of an alloy which follows this invention is set forth asincluding:

Per cent Nickel 60.00 Molybdenum 18.00 Cromium 18.00 Iron 3.00

Carbon .07 Manganese and silicon together .93

The drawing illustrates a surface of the alloy of the present inventionwhich has been enlarged 200 times. An examination of this drawingindicates that a second phase is present. It is important to note thatthe grain lines are not clearly delineated. I

The alloy provided by this invention may be described as beingcharacteristically half nonferrous and half stainless steel. Thus, manyof the desirable properties of a non-ferrous alloy such as monel areexhibited and many of the desirable properties of stainless steel arealso present. The alloy has a high tensile strength and acorrespondingly high yield point. Its casting shrinkage is down withinreasonable limits and it has good welding properties as well as beingmachinable. Its hardness is of a high Brinell and the co-eflicient ofexpansion is relatively small. All of these characteristics are highlydesirable of an alloy of this type. The main factor, however, is thatthe alloy is highly resistant to corrosion and is well able to withstandthe attack of acids.

While a preferred specific embodiment of the invention is hereinbeforeset forth, it is to be clearly understood that the invention is not tobe limited to the exact proportions described because variousmodifications of these details may be provided in putting the inventioninto practice within the purview of the appended claim.

What is claimed is:

A nickel base alloy comprising an iron content of .3 per cent, a carboncontent ranging from .04 to .10 per cent, molybdenum from 17 to 18 percent and chromium from 17 to 18 per cent, a silicon content of 1.5 percent, a manganese content of .75 per cent with the balance being made upof nickel.

GUY A. BAKER. JAMES A. PARSONS.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,115,239 Parr Oct. 27, 19141,955,856 Moore Apr. 24, 1934 2,108,051 Egeberg et a1. Feb. 15, 19382,196,699 Franks Apr. 9, 1940 2,309,136 Neiman Jan. 26, 1943 2,392,821Kreag Jan. 15, 1946 2,403,128 Scott et al July 2, 1946

